NMEA 0183 is a combined electrical and data specification for communication between marine electronic devices such as echo sounder, sonars, anemometer, gyrocompass, autopilot, GPS receivers and many other types of instruments. It has been defined by, and is controlled by, the U.S.-based National Marine Electronics Association. It replaces the earlier NMEA 0180 and NMEA 0182 standards. In marine applications it is slowly being phased out in favor of the newer NMEA 2000 standard.

NMEA-0180 and 0182 are very limited, and just deal with communications from a Loran-C (or other navigation receiver, although the standards specifically mention Loran), and an autopilot.

NMEA 0183 versions:
NMEA 2.00 Published January 1992 (NMEA 0183 migrated from RS 232 to RS422)
NMEA 2.01 Published August 1994
NMEA 2.10 Published October 1995
NMEA 2.20 Published January 1997
NMEA 2.30 Published March 1998
NMEA 3.00 Published July 2000
NMEA 3.01 Published January 2002
NMEA 4.00 Puiblished November 2008

NMEA 2000 is a protocol used to create a network of electronic devices—chiefly marine instruments—on a boat. Various instruments that meet the NMEA 2000 standard are connected to one central cable, known as a backbone. The backbone powers each instrument and relays data among all of the instruments on the network. This allows one display unit to show many different types of information. It also allows the instruments to work together, since they share data. NMEA 2000 is meant to be "plug and play" to allow devices made by different manufacturers to talk and listen to each other.

NMEA protocol can be sent by different equipment. It can be identified by so called Talker Id. Most known one is, of course $GP___ - GPS.

• GL - GLONASS Receiver
• GP - Global Positioning System (GPS)
• Heading Track Controller (Autopilot): General - AG, Magnetic - AP
• AI - Automatic Identification System
• CD - Digital Selective Calling (DSC)
• CR - Data Receiver
• CS - Satellite
• CT - Radio-Telephone (MF/HF)
• CV - Radio-Telephone (VHF)
• CX - Scanning Receiver
• DE - DECCA Navigator
• DF - Direction Finder
• EC - Electronic Chart System (ECS)
• EI - Electronic Chart Display & Information System (ECDIS)
• EP - Emergency Position Indicating Beacon (EPIRB)
• ER - Engine room Monitoring Systems
• GN - Global Navigation Satellite System (GNSS)
• HC - HEADING SENSORS: Compass, Magnetic
• HE - Gyro, North Seeking
• HN - Gyro, Non-North Seeking
• II - Integrated Instrumentation
• IN - Integrated Navigation
• LC - Loran C
• P - Proprietary Code
• RA - Radar and/or Radar Plotting
• SD - Sounder, depth
• SN - Electronic Positioning System, other/general
• SS - Sounder, scanning
• TI - Turn Rate Indicator
• VD - VELOCITY SENSORS: Doppler, other/general
• VM - Speed Log, Water, Magnetic
• VW - Speed Log, Water, Mechanical
• VR - Voyage Data Recorder
• YX - Transducer
• ZA - TIMEKEEPERS, TIME/DATE: Atomic Clock
• ZC - Chronometer
• ZQ - Quartz
• ZV - Radio Update
• WI - Weather Instruments

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